How to write a good conflict between the main couple?

Well, I really want to create a romance story, but I'm having trouble creating a good conflict between my main couple. I wanted my conflict to not be so trivial that it could be resolved in a 5-minute conversation, but also not impossible to resolve.

I haven't started writing my story yet because I have no idea what conflict will arise between them, and I don't want to bring them together so quickly after the resolution of the first conflict.

Should I start writing without this conflict and try to think of something while I write, or should I only write when I find a good conflict?

Any tips on how or which conflict to write about?